Acrylamide Formation In French Fries Research Articles

The Impact of Fat Deterioration on Formation of Acrylamide in Fried Foods

AbstractThe current study investigates to what extent the reaction products of thermal degradation directly influence acrylamide formation in French fries. The frying tests at 170 and 180 °C are carried out with rapeseed oil for 32 h with 128 frying cycles. Acrylamide content in French fries is determined by LC‐MS/MS. Oxidative and thermal degradation is followed by measuring total polar compounds (TPC), di‐ and polymerized triacylglycerols (DPTG), monomer oxidized triacylglycerols (MONOX), p‐anisidine value (AnV), mono and di‐acyl‐glycerols (MAG and DAG), acid value (AV), epoxy fatty acids, iodine value (IV), saponification value, and fatty acid composition. During frying, the nature and degradation level of the frying medium have a direct impact on acrylamide formation. It can be shown that the pH‐dependent reaction is strongly inhibited at acid values above 0.5 mg KOH g−1 oil. Acidity measured as AV or FFA is mainly caused by oxidation, and less so by hydrolysis of triacylglycerols (TAG) as assumed up to now. Obviously, acid functional groups formed by oxidation of unsaturated fatty acids bound in TAG can act not only as catalyst for dimerization of TAG but also interact with asparagine as most important precursor for acrylamide formation so that no reaction with carbonyl groups for the formation of acrylamide is necessary.Practical applications: The same acidic functional groups that are known to catalyze the formation of dimeric TAG under frying conditions (160–190 °C, access of oxygen) in a nonradical mechanism apparently can also deactivate asparagine by protonization as a potential precursor for the formation of acrylamide. It is recommended not to reduce acidity of used frying oil by active filter aids below AV ≥ 0.5 as it helps to reduce acrylamide contamination of fried food.

Vacuum impregnation pre-treatment: A novel method for incorporating mono- and divalent cations into potato strips to reduce the acrylamide formation in French fries

Abstract The effect of different vacuum impregnation (VI) pre-treatments of potato strips [in water (control), NaCl, KCl or CaCl2 (0.1 M) for 10 and 15 min] on acrylamide formation in French fries after deep frying in sunflower oil at 175°C for 5 min was determined. The acrylamide content of fries prepared with potato strips pre-treated by VI in distilled water decreased from 0.82 to 0.24 µg/g when time increased to 15 min. Moreover, the acrylamide content of fries from 10 min-KCl pre-treatment (0.35 µg/g) decreased significantly to 0.04 µg/g when time was 15 min (p < 0.05). In comparison to control (10 min), the VI pre-treatment in KCl and NaCl for 15 min reduced the relative content of acrylamide by 95 and 91%, respectively, and VI in distilled water was able to decrease this value by 71%. Results indicated that monovalent cations (K and Na) were more effective in reducing acrylamide formation than divalent cation (Ca2+) when the VI pre-treatment time increased to 15 min. In conclusion, VI as a pre-treatment for mono- and divalent cations in fried potato production could be a useful technique in industrial applications to reduce acrylamide formation in fries in a short time.

THE INFLUENCE OF POTATO SLICE SIZE ON THE ACRYLAMIDE LEVEL OF POTATOES FRIED UNDER FAST FOOD CONDITIONS

The aim of this study was to investigate the influence of potato slices (7, 9, 11 mm- Queen Anne variety) fried in palm oil in a fryer set at 190°C, for different periods of time (6, 8, 11 min) on the acrylamide level and color parameters of French fries. The experimental samples were prepared by the SPE technique and analyzed in terms of acrylamide content by GC-MS/MS. Results showed that the acrylamide content is significantly affected by the size of the potato slices and by the frying times: for 6 min of frying it varied from 222.90 µg/kg (7 mm) to 217.81 µg/kg (9 mm) and 192.36 µg/kg (11 mm), respectively; for 8 min of frying it ranged from: 842.44 µg/kg (7 mm) to 416.23 µg/kg (9 mm) and 343.19 µg/kg (11 mm); for 11 min of frying it was between 2636.06 µg/kg (7 mm), 1114.41 µg/kg (9 mm) and 906.70 µg/kg (11 mm), respectively. A reduction in the acrylamide level was obtained by about 14%, 59%, 66% for 6, 8, 11 min of frying at the size of 11 mm, compared to those divided at the size of 7 mm. The acrylamide formation in French fries was significantly reduced with larger the size of the potato slices and with shorter periods of frying. When increasing the potato slice size, positive linear correlations were obtained between the acrylamide level and the color parameters a* and b* (R² = 0.54 - 0.99) and negative linear correlations with the color parameter L* (R² = 0.684- 0.998).

Comparative evaluation of conventional and advanced frying methods on hydroxymethylfurfural and acrylamide formation in French fries

In this study, deep fat frying, microwave frying, air frying, and vacuum frying processes were used to mitigate acrylamide (AA) and hydroxymethylfurfural (HMF) formation during the frying of French fries. The highest reduction of AA and HMF range was found in vacuum frying (61.42–81.14%), followed by air frying (59.2–78.7%), as compared to deep fat frying and microwave frying. Both these method samples also showed significantly (p < 0.05) lower browning index (BI) and CIE a* values. Principal component analysis (PCA) was used to visualize the effects of the different frying methods on AA and HMF content. Vacuum frying and air frying were found to be alternative frying technologies to minimize AA and HMF content in French fries.

The influence of consecutive use of different oil types and frying oil in French fries on the acrylamide level

In the literature, the effects of different frying oil types and consecutive frying sessions on acrylamide formation are still controversial. In this study, 8 consecutive frying sessions were applied with 4 different commercial oil products (sunflower oil, olive oil, corn oil, hazelnut oil) known to be used in French fries, and the formed acrylamide level in French fries was determined by LC–MS/MS. The relationship between variables was analyzed statistically. Acrylamide levels were measured as 890−1200 μg/kg in sunflower oil, 892−1163 μg/kg in olive oil, 981−1299 μg/kg in corn oil, and 779−1120 μg/kg in hazelnut oil. The poly-unsaturated fatty acid ratio of frying oil is thought to have a positive effect on acrylamide formation. The consecutive use of frying oil significantly affected acrylamide formation in French fries. In this study, consumers may be advised to use hazelnut and olive oil, and avoid corn oil, according to acrylamide levels detected in the French fries. Nevertheless, frying oil should not be used consecutively in French fries. These results can be used in studies to reduce acrylamide exposure from French fries.

The effect of borage, ginger and fennel extracts on acrylamide formation in French fries in deep and electric air frying

The aim of this study was to evaluate the effect of three Lebanese wild plant extracts on acrylamide (AA) content in French fries, and to investigate the impact of air frying (AF) and deep frying (DF) techniques against AA formation. HPLC showed higher level of AA in DF (1384.79 ng/g) than in AF (163.1 ng/g). Indeed, the plant extracts of ginger, borage and fennel succeeded to decrease AA (59.67, 67.99, and 73.36% in (AF) and 21.91, 66.29 and 29.15% in (DF) respectively)in both fryers. Accordingly, borage fennel and ginger with their high scavenging activity (86.09%, 89.11% 93.67% respectively) and total phenolic contents (298.61, 117.79 and 97.36 of GAE respectively) can act as healthy beneficial pre-treatment, overall reducing AA in potato fries particularly in AF. This study was the first to reveal the importance of using plant extract in reducing AA in potato fries, a staple Lebanese food.

Computer Simulation with a Temperature-Step Frying Approach to Mitigate Acrylamide Formation in French Fries.

A heat and mass-transfer model coupled with reaction kinetics was developed to simulate frying. Obtaining an accurate mathematical model of the Maillard reaction and the heat and mass transfer is crucial for predicting the transient acrylamide formation, temperature, and water content in French fries. The objective of this study was to mitigate the formation of acrylamide in a potato strip by adopting a temperature step frying approach (TSFA). A considerable increase in the water content and a decrease in the temperature and acrylamide formation were observed in a potato strip fried with the TSFA compared with a potato strip fried without the TSFA process. The acrylamide content in a potato strip when fried using the TSFA decreased considerably to 57% of that in a potato strip fried without using the TSFA. Simulation of the acrylamide distribution in a potato strip revealed that the crust contains the highest amount of acrylamide. The proposed model can be successfully used to obtain high-quality products, mitigate acrylamide formation, and save energy.

Efficient inhibition of acrylamide formation in French fries by dipping in lactic acid solution before and after par-frying in a two-step procedure

Efficient inhibition of acrylamide formation in French fries by dipping in lactic acid solution before and after par-frying in a two-step procedure

Acrylamide mitigation in French fries using native l-asparaginase from Aspergillus oryzae CCT 3940

The Maillard reaction is responsible for color and flavor formation in fried, roasted and baked foods. However, this reaction can also promote the formation of acrylamide, a potential human carcinogen. The application of l-asparaginase represents a promising method for acrylamide mitigation in heated products by the direct conversion of the precursor l-asparagine to l-aspartic acid and ammonia, which does not lead to additional acrylamide formation. Our research group produced and purified an l-asparaginase from native Aspergillus oryzae CCT 3940 with highly potential for acrylamide mitigation. To verify the enzymatic effectiveness, we compared the native l-asparaginase with the commercial recombinant enzyme. For this purpose, a GC-MS/MS method was developed, optimized and validated for the assessment of acrylamide in French fries. Our results indicate a relationship between the l-asparagine content and acrylamide formation in French fries. The acrylamide concentration of the fried potato treated with the l-asparaginase from A. oryzae CCT 3940 and treated with commercial enzyme reduced 72% and 92%, respectively compared to control sample. Moreover, the l-asparaginase from A. oryzae CCT 3940 showed no l-glutaminase activity, while commercial enzyme promoted a decrease in the l-glutamine content (25%). Our results suggest that l-asparaginase from A. oryzae CCT 3940 may be of great value for acrylamide mitigation.

Influence of the frying process and potato cultivar on acrylamide formation in French fries

Acrylamide formation during the production of French fries is attributed to Maillard reactions from reducing sugars and asparagine and is dependent on the frying temperature. Low reducing sugars content in potatoes has been recommended to produce fried potato products. However, the influence of the complexity of the potato medium in the chemical reactions that promote the acrylamide formation during deep frying are not well understood. In this study, three potato cultivars (Kennebec, Red Pontiac and Agria) commonly used for fried potato products were evaluated to determine the relationships between the precursors of acrylamide in the fresh potato tubers and the properties of the fried potato strips with the acrylamide content after frying. Frying experiments were conducted at three conditions (time-temperature) to obtain French fries of similar visual colour. Acrylamide formation increased with frying temperature but different behaviour was observed between cultivars. For Red Pontiac, a remarkably increase in acrylamide content was found at 170 °C (∼40%) together with the increase in colour. However, lower oil uptake and higher moisture content was obtained as temperature increase. Significant positive correlations were observed between the acrylamide level and the reducing sugars and sucrose content on fresh potatoes (0.652, 0.699, p ≤ 0.01, respectively). The acrylamide content obtained in Agria cultivar may be obtained from the hydrolysis of sucrose during the frying process. In fried potato strips, positive significant correlation was found between the shear force and acrylamide (0.749, p ≤ 0.01). The significant correlations obtained between colour, and texture, colour and oil uptake and texture and acrylamide content indicate the intrinsic relationship between the properties of the fried potato strips and the acrylamide content.

Influence of deep-frying using various commercial oils on acrylamide formation in French fries

This study investigated the effect of different types of commercial oils (rice bran oil, shortening oil, high-oleic rapeseed oil, low-erucic acid rapeseed oil, blend oil A and blend oil B) and frying cycles on acrylamide formation during the preparation of French fries by deep-frying. Frying was carried out in intermittent mode (two batches each for 12 min without any time lag) and repeated for 600 frying cycles. Results indicated that the French fries that were fried in oils having lower heat transfer coefficients contained lower acrylamide concentrations (913 µg kg–1), whereas those fried with oils having higher heat transfer coefficients contained higher acrylamide concentrations (1219 µg kg–1). Unlike the peroxide value, acrylamide levels in French fries did not change significantly with an increase in the number of frying cycles when tested for 600 frying cycles for every type of oil. This study clearly indicates that the contribution of frying oils to the formation of acrylamide should not be neglected due to their different heat transfer coefficients. On the other hand, continuous use of frying oil does not lead to a higher acrylamide concentration in French fries.

Role of polyphenols in acrylamide formation in the fried products of potato tubers with colored flesh

The levels of asparagine, reducing sugars and total phenolics in some potato cultivars and advanced selections with distinctive flesh color (white, yellow, red and purple) and their potential in acrylamide formation in French fries and potato chips have been investigated in this study. The range of asparagine and reducing sugars were 1.8–9.0 and 1.35–11.7mg/g respectively. There was no significant correlation of asparagine and reducing sugars with flesh color of the potato tubers. Tubers with red and purple flesh had higher levels of total phenolics than the white and yellow ones. The amount of acrylamide formed in French fries and chips were ranged from 128.1 to 1651.3μg/kg and from 2104.3 to 2978.5μg/kg respectively. The levels of asparagine and reducing sugars were positively correlated with acrylamide formation while total phenolics and chlorogenic acid correlated negatively.

A Monte Carlo Risk Assessment Model for Acrylamide Formation in French Fries

The objective of this study is to estimate the likely human exposure to the group 2a carcinogen, acrylamide, from French fries by Irish consumers by developing a quantitative risk assessment model using Monte Carlo simulation techniques. Various stages in the French-fry-making process were modeled from initial potato harvest, storage, and processing procedures. The model was developed in Microsoft Excel with the @Risk add-on package. The model was run for 10,000 iterations using Latin hypercube sampling. The simulated mean acrylamide level in French fries was calculated to be 317 microg/kg. It was found that females are exposed to smaller levels of acrylamide than males (mean exposure of 0.20 microg/kg bw/day and 0.27 microg/kg bw/day, respectively). Although the carcinogenic potency of acrylamide is not well known, the simulated probability of exceeding the average chronic human dietary intake of 1 microg/kg bw/day (as suggested by WHO) was 0.054 and 0.029 for males and females, respectively. A sensitivity analysis highlighted the importance of the selection of appropriate cultivars with known low reducing sugar levels for French fry production. Strict control of cooking conditions (correlation coefficient of 0.42 and 0.35 for frying time and temperature, respectively) and blanching procedures (correlation coefficient -0.25) were also found to be important in ensuring minimal acrylamide formation.

The effect of asparaginase on acrylamide formation in French fries

Acrylamide formation in French fries was investigated in relation to blanching and asparaginase soaking treatments before final frying. Par-fried potatoes of Bintje variety were prepared by cutting strips (0.8×0.8×5cm) which were blanched at 75°C for 10min. Unblanched strips were used as the control. Control or blanched strips were then dried at 85°C for 10min and immediately partially fried at 175°C for 1min. Finally, frozen par-fried potatoes were fried at 175°C for 3min to obtain French fries. Pre-drying of raw or blanched potato strips did not generate acrylamide formation as expected. Partial frying of pre-dried control potato strips generated 370μg/kg of acrylamide and the final frying determined French fries with 2075μg/kg of acrylamide. When control potato strips were treated with a 10000 ASNU/l asparaginase solution at 40°C for 20min, the acrylamide formation in French fries was reduced by 30%. When blanched potato strips were treated in the same way, the produced French fries have 60% less acrylamide content than blanched strips without the enzyme treatment. Soaking of blanched potato strips (75°C, 10min) in an 10000 ASNU/l asparaginase solution at 40°C for 20min is an effective way to reduce acrylamide formation after frying by reducing the amount of one of its important precursors such as asparagine.

Reduction of acrylamide formation in French fries by microwave pre‐cooking of potato strips

AbstractIn this study, the effect of microwave pre‐cooking of potato strips on the resultant acrylamide levels in French fries was investigated. Control and microwaved (10, 20, and 30 s at 850 W) samples were fried at 150, 170 and 190 °C for predetermined times. Surface and core temperatures of potato strips were acquired during frying, and acrylamide content in the surface and the core regions were determined separately. The results showed that microwave application prior to frying resulted in a marked reduction of acrylamide level in the surface region, whereas a slight increase was noted for the core region. When the potato strips were subjected to frying after a microwave pre‐cooking step, acrylamide content in the whole potato strip was reduced by 36%, 41%, and 60% for frying at 150, 170, and 190 °C, respectively, in comparison to the control. Copyright © 2006 Society of Chemical Industry

Acrylamide reduction under different pre-treatments in French fries

Acrylamide formation in French fries was investigated in relation under different processing conditions and the content of glucose and asparagine of the strips before frying. Potato strips (0.8 × 0.8 × 5 cm) of Bintje variety were fried at 150, 170 and 190 °C until reaching moisture contents of ∼40 g water/100 g (total basis). Prior to frying, potato strips were treated in one of the following ways: (i) immersed in distilled water for 0 min (control), 60 min and 120 min; (ii) immersed in a citric acid solution of 10 g/L for an hour; (iii) immersed in a sodium pyrophosphate solution of 10 g/L for an hour; (iii) blanched in hot water at six different time-temperature combinations (50 °C for 40 and 80 min; 70 °C for 10 and 45 min; 90 °C for 3 and 10 min). Acrylamide content was determined in French fries while the glucose and asparagine content in the potato strips before frying. Immersed strips in water for 120 min showed a reduction of acrylamide formation of 33%, 21% and 27% at 150, 170 and 190 °C, respectively, when they were compared against the control. Potato strips blanched at 50 °C for 80 min had the lowest acrylamide content when compared against strips blanched at different conditions and fried at the same temperature (135, 327 and 564 μm acrylamide/kg for 150, 170 and 190 °C, respectively). Potato strip immersion in citric acid solution of 10 g/L reduced much more the acrylamide formation after frying than the strip immersion in sodium pyrophosphate solution of 10 g/L (53% vs. 17%, respectively—average values for the three temperatures tested). Acrylamide formation decreased dramatically as the frying temperature decreased from 190 to 150 °C for all the pre-treatments tested. Color represented by the total color difference showed high correlation ( r 2 of 0.854) with the acrylamide content of French fries.

Selection Criteria for Potato Tubers To Minimize Acrylamide Formation during Frying

A number of parameters linked to the selection of potato tubers were evaluated with regard to their potential to influence acrylamide formation in French fries. The formation of acrylamide, which is a potential human carcinogen, can be minimized for a big extent by the selection of an appropriate tuber. This study focused on the following selection criteria: variety as influenced by storage time and soil type, underwater weight, and tuber size. A total of 16 varieties were compared, concerning their potential for acrylamide formation. From that survey, certain varieties, such as Tebina and Quincy, could be appointed as unsuitable for frying. The differences in the potential of acrylamide formation between the varieties could mainly be explained by the reducing sugar content of the potato (R2 = 0.82, n = 96). The investigated type of soil and storage time at 8 degrees C appeared to have a minor influence on the acrylamide formation during frying. On the other hand, the tuber size of the potato did contribute in a significant manner to the acrylamide formation. Smaller tubers were more susceptible to acrylamide formation and should be avoided in the frying process. The last selection parameter, the underwater weight, appeared to be of minor importance in the acrylamide formation. On the basis of these simple selection criteria, it is possible to make a first screening of potatoes to reduce the acrylamide formation during frying.

Influence of the frying temperature on acrylamide formation in French fries

It is well established that high oil temperatures during frying strongly increase acrylamide formation in French fries, but it is less clear, which temperature or rather which part of a temperature profile is relevant and if rules or regulatory measures should be established in respect of frying temperature, on which temperature they should refer. In most fryers, the oil temperature strongly drops on adding the potato sticks and may not fully recover up to the end of the frying process (depending on the amount of potato added in relation to the volume of oil and the heating power of the fryer). Since acrylamide is formed towards the end of frying, the temperature during the second half of the process is more important than that regulated by the thermostat. The profile of the frying temperature was optimized regarding product quality (crispness, flavor) and acrylamide formation. An initial temperature of 170–175 °C dropping to 140–145 °C and a virtually isothermal frying at 160 °C resulted in products of similar quality and acrylamide content. At initial temperatures below 160 °C and with main frying temperatures below 140 °C, crispness and the flavor of the French fries suffered: the sticks dried out and became oily. Isothermal frying at 167–170 °C resulted in approximately doubled acrylamide content compared to conditions that were optimal in respect of culinary quality and low acrylamide formation, showing that rules on the initial temperature alone are inadequate to ensure low acrylamide contents. Optimized fryers should program temperature: allowing an initial temperature drop, but then efficiently heating to prevent the temperature dropping below a given limit; after the end of frying, the initial temperature must be restored before frying the next portion.

Influence of Storage Practices on Acrylamide Formation during Potato Frying

A number of parameters linked to storage of potatoes were evaluated with regard to their potential to influence the acrylamide formation in French fries. Acrylamide, which is a potential human carcinogen, is reported to be formed during the frying of potatoes as a result of the reactions between asparagine and reducing sugars. This study was conducted using three potato varieties (Bintje, Ramos, and Saturna) typically used in Belgium, The Netherlands, and the northern part of France for French fry and crisp production. Saturna, mainly used in crisp production, appeared to be the least susceptible for acrylamide formation during frying. Especially storage at low temperatures (4 degrees C) compared to storage at 8 degrees C seemed to enhance acrylamide formation due to a strong increase in reducing sugars caused by low-temperature storage. Because of the reversible nature of this physiological reaction, it was possible to achieve a significant reduction of the reducing sugars after a reconditioning of the cold-stored potatoes for 3 weeks at 15 degrees C. All changes in acrylamide concentrations could mainly be explained by the reducing sugar content of the potato (R2 = 0.84, n = 160). This means that, by ensuring a low reducing sugar content of the potato tuber, the risk for acrylamide formation will largely be reduced. Finally the use of a sprout inhibitor did not influence the composition of the potato, and thus acrylamide formation was not susceptible to this treatment.

Acrylamide in French fries: influence of free amino acids and sugars.

The free amino acid profile and sugar (fructose, glucose, and sucrose) composition were determined in potato samples selected to give a large range of variation (a total of 66 samples). From these samples French fries were produced in a laboratory-scale simulation of an industrial process followed by a finish fry at 180 degrees C for 3.5 min using a restaurant fryer. The final product was blast frozen and analyzed for acrylamide. Acrylamide was detected in all samples, but its concentration varied significantly from 50 to 1800 ng/g. For isotope dilution (13C3) acrylamide analysis, samples were extracted with water, cleaned up on HLB Oasis polymeric and Accucat mixed mode anion and cation exchange SPE columns, and analyzed by LC-MS/MS. Statistical analysis of the data indicates that the effect of sugars and asparagine on the concentration of acrylamide in French fries is positive and significant (p < 0.001). It appears that one of the ways acrylamide formation in French fries can be effectively controlled is by the use of raw products with low sugar (and to a lesser degree, asparagine) content.